1. Field of the Disclosure
The present disclosure relates generally to a method and an apparatus for receiving a signal in a wireless communication system, and more particularly, to a method and an apparatus for receiving a signal by using iterative detection and decoding in a wireless communication system.
2. Description of the Related Art
Due to the recent rapid growth of the wireless mobile market, various multimedia services in a wireless environment are required. Particularly, improvements in large capacity data transmission and high speed data transmission are being progressed. Accordingly, a scheme capable of efficiently using limited frequencies uses, for example, a Multiple Input Multiple Output (MIMO) system using multiple antennas.
The MIMO technology refers to a system in which each of the transmitting and receiving sides uses multiple antennas, which may increase channel transmission capacity in proportion to the number of antennas without additional allocation of frequencies or transmission power in comparison with a system using a single antenna.
The multiple antenna technologies are divided into a spatial diversity scheme that acquires diversity corresponding to the product of the number of transmission/reception antennas to improve transmission reliability, a Spatial Multiplexing (SM) scheme that simultaneously transmits a plurality of signal columns to improve a transmission rate, and a scheme generated by combining the spatial diversity and the spatial multiplexing.
When the SM scheme is used, if respective transmitters transmit different data columns from each other, interference is generated between simultaneously transmitted data. Accordingly, the receiver detects a signal by using Maximum Likelihood (ML) considering an influence signal effect or performs detection after removing the interference. For a reference, the reference may be removed by zero forcing, Minimum Mean Square Error (MMSE) or the like.
However, since the reception schemes do not use a priori information on transmission bits, the reception performance may be improved. In order to improve the reception performance, an Iterative Detection and Decoding (IDD) scheme may be applied.
To facilitate understanding, the IDD scheme is briefly described below.
In the IDD scheme, a turbo principle is applied to a MIMO receiver, and a receiver of the iterative detection and decoding scheme has a configuration in which a detector and a decoder are concatenated. The detector generates soft decision information of a received signal and transmits the generated soft decision information to the decoder. The soft decision information may be generated by a Log Likelihood Ratio (LLR).
Then, the decoder generates a new soft decision value by decoding each bit of the received signal using the soft decision information provided from the detector. Thereafter, the new soft decision value generated by the decoder is fed back to the detector and used as a priori information for iterative detection and decoding. The process is repeated a predetermined number of times to increase the reliability of the received signal.